Commercial warewashers commonly include a housing area which defines a chamber for washing and rinsing of dishes, pots, pans and other wares. In a typical batch-type machine, such as an undercounter machine, a single cleaning zone or spray zone is provided in the machine and loads of wares are moved into and out of the machine through an opening that is closable by a door, with the ware remaining stationary in the spray zone during the cleaning cycle of the machine. In the commercial environment, ware loads are often cleaned sequentially one after the other, with personnel opening the machine door promptly after completion of a cleaning cycle so that the clean load of wares (e.g., in a removable and transportable rack) can be removed and a new load of soiled wares (e.g., in a different rack) can be inserted for initiation of a next cleaning cycle. This type of operation can result in significant energy losses in the form of warm, moist air that escapes the chamber when the door is opened at the end of a cycle. The heat and moisture transferred into the surrounding room also increases the amount of conditioning required to maintain a comfortable working environment in the kitchen.
It would be desirable to provide a simple arrangement for retaining some of the warm moist air within the chamber during load changes so as to reduce energy losses.